Stage-specific localization of cytoskeletal actin mRNA in murine seminiferous tubules and intestinal epithelia as demonstrated by in-situ hybridization

Summary In-situ hybridization experiments have been performed using isoactin ( and )-specific riboprobes in various tissues of the rat and mouse. Distribution of the grains of actin mRNAs for both and types was similar throughout sections of the rat testis. Although both mRNAs were evenly distributed in the seminiferous tubule, extremely heavy labeling was observed in about 10% of the seminiferous tubules that could be identified as stage XII of spermatogenesis. At high magnification, grains of the mRNA were found in the cytoplasm of elongating spermatids and in the Sertoli cell cytoplasm at the adluminal side. Much higher density of the grains of mRNA was observed in the neck region of the spermatids at stage XII. Thus, the dense distribution of cytoskeletal actin mRNAs is stage-specific in the tubule during spermatogenesis in the rat. The high expression of both and actin mRNAs was also observed in the epithelial cells of the intestinal crypts.     

Release of human epidermal growth factor from platelets in accordance with aggregation in vitro

We measured the intra-platelet content of human epidermal growth factor (hEGF) and beta-thromboglobulin (beta-TG) and the quantities of these released from platelets during in vitro aggregation. The intra-platelet amounts of hEGF and beta-TG in 10(8) platelets were 104.9 +/- 18.9 (Mean +/- SEM) pg and 2920.9 +/- 149.9 ng, respectively. During platelet aggregation elicited by 9, 11-epithio-11, 12-methano-thromboxane A2, a stable thromboxane A2 agonist, hEGF and beta-TG were released in amounts about 50% and 40% of the respective content in platelets. Also during arachidonate-induced aggregation, hEGF and beta-TG were released at about 60% and 50%, respectively. Various concentrations of thromboxane A2 antagonist, (9, 11), (11, 12)-di-deoxa-9, 11-dimethyl-methano-11, 12-methano-13, 14-dihydro-13-aza-14-oxo-15-cyclopentyl-16, 17, 18, 19, 20-pentanor-15-epi-thromboxane A2, suppressed both aggregation and release reactions in a dose-dependent manner. There were good correlations between the platelet aggregation rate and released beta-TG (r = 0.9368, p less than 0.01) or hEGF (r = 0.8931, p less than 0.01) and between released beta-TG and hEGF (r = 0.9385, p less than 0.01). These results suggest that hEGF is released from platelets in a similar fashion to beta-TG in vitro.     

Proteinic prorenin-releasing-stimulator (PRS) in the rat submandibular gland

The release of prorenin as well as renin from rat renal slices was confirmed by a rat prorenin-prosegment ELISA system and an assay system for determining the renin activity. A significant increase of the prorenin release was found by adding rat submandibular gland extract to the slice medium, indicating the existence of a prorenin-releasing stimulator (PRS) in the extract. The pI and molecular mass of PRS were 8.5-8.7 and 28-30 kDa, respectively. The PRS was completely inactivated by boiling or a proteinase treatment.     

Determination of guanine by high-performance liquid chromatography with electrochemical detection: application to DNA and RNA assays

A highly sensitive assay for guanine was developed using high-performance liquid chromatography with electrochemical detection (ECD). Guanine was susceptible to the electrochemical oxidation, and ECD response was proportional to the amount of guanine in the range 0.25-4 pmol of guanine. The ECD of guanine was applicable to the analysis of nucleic acids. DNA and RNA were hydrolyzed in 0.03 and 3 M HCl, respectively, and guanine liberated from the nucleic acids was separated on a reverse-phase column and determined by ECD. The method allowed detection of 0.2 ng of calf thymus DNA or tRNA. An application of the method is shown for DNA and RNA assays in trichloroacetic acid extracts of rat adrenal and liver.     

Altered hepatic microsomal function and elevated protooncogene expression as residual effects in rats exposed to delta-9-tetrahydrocannabinol

The microsomal activation of the potent hepatocarcinogen aflatoxin B1 (AFB1) and the expression of selected protooncogenes were investigated in the livers of rats exposed to delta 9-tetrahydrocannabinol (THC). At equimolar levels of cytochrome P-450, the microsome-mediated binding of AFB1 to DNA was significantly lower (56% of the controls) in preparations from drug exposed rats. Hepatic expression of the c-k-ras protooncogene was 3-fold higher in THC exposed animals. These results suggest the possible occurrence of long lasting residual effects in the rats exposed to THC.     

Functions of the COOH-terminal region of cyclodextrin glucanotransferase of alkalophilic Bacillus sp. #1011: relation to catalyzing activity and pH stability

Cyclodextrin glucanotransferase (beta-CGTase) of alkalophilic Bacillus sp. #1011 degrades starch to mainly beta-cyclodextrin (beta-CD). This enzyme is considered to contain an extra-polypeptide in its COOH-terminal region in addition to its NH2-terminal domain which exhibits the starch-degrading activity. To analyze the functions of this extra-polypeptide in the beta-CGTase, two mutated enzymes, in which DNA regions encoding 10 or 13 amino acids from the COOH-terminus were deleted, were obtained. The mutated enzymes degraded starch to glucose, maltooligosaccharides and alpha-CD, in addition to beta-CD. Furthermore, the pH stability of the mutated enzymes in the alkaline pH range (pH 9-11) was reduced.     

Tissue-specific expression of three types of beta-protein precursor mRNA: enhancement of protease inhibitor-harboring types in Alzheimer's disease brain

Expression of three types of mRNA encoding amyloid beta-protein precursor (APP) in various tissues was analysed, using a ribonuclease protection assay, with special reference to Alzheimer's disease (AD). The total content and the proportion of APP mRNAs were specific to each tissue. Among eight tissues examined, the brain was distinct in that the expression level was highest and APP695 mRNA was expressed in abundance. The ratio of APP770/APP751/APP695 mRNAs was approximately 1:10:20 in the cerebral cortex of control brain. The proportions of APP770 mRNA and APP770-plus-APP751 mRNAs increased up to 2.6- and 1.4-fold, respectively, in various regions of AD brain compared with control. The enhanced expression of protease inhibitor-harboring types (APP770 and APP751) may disturb the balance between biosynthesis and degradation of APPs and ultimately lead to accumulation of beta-protein as amyloid.     

Comparison of effects of a potassium channel opener BRL34915, a specific potassium ionophore valinomycin and calcium channel blockers on endothelin-induced vascular contraction

The effects of a potassium (K+) channel opener BRL34915 and a specific K+ ionophore valinomycin on vasoconstriction induced by endothelin (ET) were compared with those of calcium (Ca2+) channel blockers, nicardipine and verapamil, using helical strips from rat thoracic aorta. ET induced potent and persistent contraction in control solution and similar but smaller contraction in Ca2+-free solution. BRL34915 and valinomycin inhibited the ET-induced contraction dose-dependently in control solution, but not in Ca2+-free solution. The ET-induced contraction was also inhibited by nicardipine and verapamil, though less strongly. On the other hand, high K+ (35 mM)-induced vasoconstriction was strongly inhibited by nicardipine and verapamil, but not by BRL34915 or valinomycin. These results support the idea that the extracellular Ca2+-dependent component of the ET-induced contraction may be mediated by Ca2+ influx by a route other than voltage-dependent Ca2+-channels.